1. Technical Field
The present invention relates to an amorphous alloy powder, a dust core, a magnetic element, and an electronic device.
2. Related Art
Recently, the reduction in size and weight of mobile devices such as notebook personal computers is significant. Further, the performance of notebook personal computers has been improved to such an extent that it is almost equivalent to that of desktop personal computers.
In order to reduce the size and improve the performance of mobile devices in this manner, it is necessary to increase the frequency of a switching power supply. At present, the driving frequency of a switching power supply has been increased to about several hundred kilo hertz. In response to the increase in the frequency of the switching power supply, it is also necessary to increase the driving frequency of a magnetic element such as a choke coil or an inductor which is built into the mobile device.
For example, JP-A-2007-182594 discloses a ribbon composed of an amorphous alloy containing Fe, M (provided that M is at least one element selected from Ti, V, Zr, Nb, Mo, Hf, Ta, and W), Si, B, and C. It also discloses a core produced by laminating this ribbon and processing the resulting laminate by punching or the like. It is expected that by using such a core, the AC magnetic properties are improved.
However, in the core produced from the ribbon, a significant increase in the Joule loss due to an eddy current (an eddy current loss) may not be avoided in the case where the driving frequency of a magnetic element is further increased.
In order to solve such a problem, a dust core obtained by press-molding a mixture of a soft magnetic powder and a binding material (a binder) is used.
On the other hand, a soft magnetic powder composed of an amorphous alloy material has a high electrical resistance. Due to this, a core containing such a soft magnetic powder can decrease the eddy current loss, and as a result, an iron loss at a high frequency can be decreased. In particular, an Fe-based amorphous alloy has a high saturation magnetic flux density, and therefore is preferred as a soft magnetic material for magnetic devices.
However, an Fe-based amorphous alloy has a large magnetostriction. Therefore, a magnetic device formed from an Fe-based amorphous alloy has a problem that a beat is generated at a specific frequency, and also the improvement of the magnetic properties (e.g., decrease in the coercive force and increase in the magnetic permeability) is inhibited.